Home / News / Industry News / Comparison of advantages and disadvantages of rotary and linear blow molding machines

Comparison of advantages and disadvantages of rotary and linear blow molding machines

With the development of the liquid food market, PET bottles are widely used in beverage, dairy and other industries, which has created a good opportunity for the development of PET packaging machinery. At present, there are two main types of blowing machines on the market: rotary and linear. Basically, a two-step production process is used: the preform injection machine produces the preform, and the blow molding machine passes through the preform trimming, preform loading, heating, stretching, and pre-blowing. , high pressure blowing (or increased cooling), exhaust and bottle taking and other processes to produce finished PET bottles. Rotary bottle blowing machine, high output, good versatility and stability, the same machine can produce bottles with different mouths and bottle shapes, but the price is higher, suitable for customers with higher output; linear blow molding machine, moderate output , The price is low, and the compatibility is general. Due to the influence of the transmission chain and other structures, the bottles with large volume changes need to be equipped with different types of linear machines, which are suitable for customers with medium and low output. The following is an analysis and comparison of the rotary blow molding machine and the linear blow molding machine.

1. Plane layout
Due to the difference in structure, the layout of the blowing machine is very different. The rotary blowing machine is composed of four parts: a blank unwinding machine, a heating machine, a main machine and an electric machine. Each part can be separated separately to facilitate disassembly and transportation. It is suitable for continuous and high-speed production, the blowing direction is forward blowing; there are many layouts of linear blow molding machines, one is that the main engine and heating are concentrated on one machine base, intermittent production, and the blowing direction is reverse blowing; one is the main engine Layout separately from heating can realize continuous production, and the blowing direction is positive blowing; this layout is the key to improving production.

2. Production efficiency
There is a certain gap in the production efficiency of the two types of blow molding machines. The biggest advantage of the rotary blow molding machine is that it has a large number of mold cavities, high output, continuous production, and convenient operation and maintenance. At present, sidel and other blow molding machines can produce 1800 bottles/hour to 2000 bottles/hour in a single mold, and the stability of the equipment is gradually improved; the linear blow molding machine, a domestic manufacturer, has a single mold output of 800 bottles/hour to 1200 bottles/hour. When /, the number of cavities is generally 4 to 10, and some manufacturers can design 12 to 16 cavities. Foreign all-electric linear machines such as Sipa can produce more than 1,500 bottles per hour in a single mold. The structure and layout have their own unique aspects, which are worthy of study and reference.
3. Transmission system
The linear machine is mainly driven by a servo motor, and the heating chain is used for intermittent motion. A few cylinders are used to push the heating chain for intermittent motion. During the operation, the origin detection is affected by the accuracy of the chain and the workpiece, and the mold clamping is prone to clipping or blanking. Interference phenomenon with the heating chain; all-electric linear machine, the main machine and heating are driven by servo motors respectively, and the synchronization is easy to control; most of the rotary machines are driven by a gear motor, driven by a synchronous belt, and the billet and bottle run synchronously at the origin. Detection is easier.

4. Mold structure
Due to the different structures of the two types of models, the structure of the mold base is very different. The rotary machine mold base is composed of a movable mold base, a fixed mold base, a middle mold sleeve and a mold. The movable and fixed mold bases can be opened and closed around one axis. At a certain angle, each group of mold bases generally has one mold cavity, and a few foreign manufacturers can design 2 to 3 mold cavities; in order to reduce the rotational inertia, the mold base should be light in weight and have sufficient strength. The mold base of the linear machine is mostly composed of two movable mold bases and two fixed mold bases. The movable mold base can move relatively equidistantly along the guide column or guide rail, and 2 to 10 mold cavities can be arranged in the middle. The mold base material is generally Ductile iron or carbon steel welding.

5. Clamping mechanism
The mold clamping mechanism is to prevent mold expansion during the blowing process, and the size of the expansion modulus directly affects the quality of the bottle. Rotary machine clamping mainly adopts bolt type or rotary clamping, with simple structure, and the guide rail controls the unlocking and locking. In order to reduce the impact, vibration and noise during movement, the guide rail curve design should be reasonable; the linear machine clamping mainly adopts hydraulic cylinder or air cylinder Drive, because the connecting rod drives the mold base with large mass, it is easy to cause equipment vibration during operation, especially the vibration of opening and closing molds. It is necessary to add a buffer of mechanical or hydraulic system to slow down the vibration. Foreign all-electric linear machine, driven by servo motor or cam mechanism, can open and close the mold once in one rotation, and the output can be increased or decreased at any time. The vibration caused by mold opening and closing is much smaller than that of hydraulic or cylinder drive. The die way is ideal for linear machines.